one_bits variable about blockhash-js

[artfwo]

This array is just a helper for quickly comparing hexadecimal hashes. Index is the value of a xor operation on 4 consecutive bits in a pair of hashes. Value is the number of bits that differ.

For example take a look at the following hashes:

1a2b8c3d4
1a2bfc3d4

The numbers at index 4 are different: 0x8 and 0xf respectively. Their binary values are:

0x8 == 0b1000
0xf == 0b1111

The result of the xor operation will be 0x8 ^ 0xf == 0b0111 which is equal to 7. one_bits[7] is equal to 3, which is the number of different bits in 0x8 and 0xf. Hope this helps!